One way is to use CSS
In the head section of the page:
<style type="text/css">
table {border: 2px solid green; border-collapse:collapse;}
td, th {border: 1px solid red;}
</style>
Change the size, colour and border style (solid in above example) to
suit your requirements.
If it's only one table you wish to specify borders for then give the
table an id, and change the CSS to:
<style type="text/css">
#table1 {border: 2px solid green; border-collapse:collapse;}
#table1 td, #table1 th {border: 1px solid red;}
</style>
Where table1 is the id given to the table.
In the page body you will have
<table id="table1">
